Moderator Action: CFC does not condone piracy, suggestions of resorting to it, etc.
In reply to the OP, have you tried running the Civ5 exe directly from the program files directory?
I'm on win7 and for me it's located in "C:\Program Files (x86)\Steam\steamapps\common\sid meier's civilization v\CivilizationV.exe". Running this might be the oft-mentioned "offline mode", meaning it might let you play with no connection. I can't try it myself because going offline would disrupt the Civ4 pitboss games I'm hosting.
In reply to the OP, have you tried running the Civ5 exe directly from the program files directory?
I'm on win7 and for me it's located in "C:\Program Files (x86)\Steam\steamapps\common\sid meier's civilization v\CivilizationV.exe". Running this might be the oft-mentioned "offline mode", meaning it might let you play with no connection. I can't try it myself because going offline would disrupt the Civ4 pitboss games I'm hosting.